moscovium

moscovium
Name	moscovium
Number	115
Category	post-transition metal (predicted)
Group	15
Appearance	unknown, likely metallic
Atomic weight	[290] (most stable isotope)
Electron configuration	[Rn] 5f14 6d10 7s2 7p3 (predicted)
Phase	solid (predicted)
Melting point	670 K (400 °C, 750 °F) (predicted)
Boiling point	~1400 K (~1100 °C, ~2000 °F) (predicted)

moscovium is a synthetic chemical element with the symbol Mc and atomic number 115. It was first synthesized in 2003 by a joint team of Russian and American scientists at the Joint Institute for Nuclear Research (JINR) in Dubna, near Moscow. The element is highly radioactive and unstable, with all known isotopes decaying in seconds or milliseconds, placing it within the theorized island of stability region on the periodic table. Its chemical properties are predicted to resemble those of bismuth, though its extreme instability has prevented bulk chemical study.

History

The discovery of moscovium was reported in 2003 by a collaboration between scientists at the Joint Institute for Nuclear Research and Lawrence Livermore National Laboratory. The team, led by Yuri Oganessian, bombarded a target of americium-243 with ions of calcium-48 using the U400 cyclotron at the Flerov Laboratory of Nuclear Reactions. This work built upon earlier theoretical predictions by Glenn T. Seaborg and others regarding superheavy elements. In 2015, the discovery was jointly verified by the International Union of Pure and Applied Chemistry (IUPAC) and the International Union of Pure and Applied Physics (IUPAP). The name moscovium, honoring the Moscow Oblast region, was formally adopted by IUPAC in 2016 following a proposal by the discoverers.

Properties

Predicted physical properties of moscovium suggest it would be a dense, solid metal at room temperature, potentially exhibiting a face-centered cubic crystal structure. Theoretical calculations, often using relativistic quantum chemistry models like the Dirac equation, indicate significant relativistic effects due to high nuclear charge, which contract the 7s and 7p orbitals and influence its bonding behavior. These effects, including spin-orbit coupling, are expected to cause deviations from trends set by lighter pnictogens like bismuth and antimony. Its predicted melting and boiling points are notably higher than those of nitrogen and phosphorus, aligning more closely with its immediate periodic neighbors.

Synthesis and nuclear reactions

All moscovium isotopes have been produced via fusion-evaporation reactions in particle accelerators. The primary method involves bombarding a rotating target of americium-243 with a high-energy beam of calcium-48 nuclei. This fusion creates a excited compound nucleus, such as moscovium-288, which then evaporates several neutrons to reach a more stable state. The resulting atoms are separated from the beam and other reaction products using advanced techniques like the gas-filled recoil separator at facilities such as the GSI Helmholtz Centre for Heavy Ion Research. Detection relies on measuring characteristic alpha decay chains that terminate in spontaneous fission events, often linked to known isotopes of nihonium and roentgenium.

Chemical properties

Moscovium is projected to be the third member of the period 7 elements in group 15. Computational studies, including those based on density functional theory, predict its most stable oxidation state will be +I, rather than the +III or +V states common to pnictogens, due to the inert-pair effect and relativistic stabilization of the 7s electrons. This would make its chemistry distinct from bismuth. Predicted compounds might include McCl and McF, which are expected to be more volatile than those of thallium. Experimental chemistry, performed one atom at a time using gas-phase chromatography setups like OLGA or the Cryo-TASIS apparatus, remains extremely challenging due to short half-lives and low production rates.

Isotopes

Several isotopes of moscovium are known, with mass numbers ranging from 286 to 290. The most stable isotope identified to date is moscovium-290, with a half-life of approximately 0.65 seconds, decaying via alpha emission to nihonium-286. Other isotopes, like moscovium-289 and moscovium-288, have half-lives measured in milliseconds. The synthesis of heavier isotopes, potentially approaching the island of stability centered near copernicium-291 or flerovium-298, is a major goal of superheavy element research at facilities like RIKEN and the Superheavy Element Factory at JINR. These isotopes may exhibit significantly longer half-lives, enabling more detailed chemical investigation.

See also

* Oganesson * Tennessine * Flerovium * Nihonium * Dubna * Transactinide element * Superheavy element

Category:Chemical elements Category:Synthetic elements Category:Post-transition metals